1、 disable DNS service，network DNS disable under master account；
2、 delete all share of file system；
3、 share IP of file system as regulation；
4、client mounts file system again and it is no problem.

Root Cause

1、client mount time out：when client visits nfs server，if dns is open，nfs server will inquire about client name in dns，but dns 192.168.1.1 does not exist，it is about 10 seconds for inquire time out，so client is going to be overtime and cannot mount .
2、client permission is denied， and it is probably because ofDNS enable.

Suggestions

DNS is on after N8000 initialization. If you don’t need DNS service，you should set DNS to Disable by hand.